As a result of the Malaysian government specifying that the buildings be completed in six years, two construction consortiums were hired in order to meet the deadline, one for each tower. Tower 1, the west tower (right in the top-right photograph) was built by a Japanese consortium led by the Hazama Corporation (JA Jones Construction Co., MMC Engineering Services Sdn Bhd, Ho Hup Construction Co. Bhd and Mitsubishi Corp) while Tower 2, the east tower (left in the top-right photograph) was built by a South Korean consortium led by the Samsung C&T Corporation (Kukdong Engineering & Construction and Syarikat Jasatera Sdn Bhd). Early into construction a batch of concrete failed a routine strength test causing construction to come to a complete halt. All the completed floors were tested but it was found that only one had used a bad batch and it was demolished. As a result of the concrete failure, each new batch would now be tested before being poured. The halt in construction had cost US$700,000 per day and led to three separate concrete plants being set up on the site to ensure that if one produced a bad batch, the other two could continue to supply concrete. The sky bridge contract was completed by Kukdong Engineering & Construction. Tower 2 became the first to reach the world's tallest building at the time. But Tower 1 ran into problems when they discovered the structure was leaning 25 millimetres (0.98 in) off from vertical. To correct the lean, the next 16 floors were slanted back 20 millimetres (0.79 in) with specialist surveyors hired to check verticality twice a day until the building's completion.[8]